ISTQB Black-Box Test Design 4 — Questions and Answers
Question 1: A password field requires 8 to 16 characters. Using 3-value BVA, which set of test values is complete?
- 7, 8, 16, 17
- 7, 8, 9, 15, 16, 17 (Correct answer)
- 8, 12, 16
- 7, 9, 15, 17
Correct answer: 7, 8, 9, 15, 16, 17
3-value BVA tests the value below, at, and above each boundary: 7, 8, 9 for the lower boundary and 15, 16, 17 for the upper boundary.
Question 2: Which statement about invalid equivalence partitions is CORRECT?
- They should be combined into a single test case for efficiency
- Each invalid partition should be covered by a separate test case (Correct answer)
- Invalid partitions are optional to test in black-box testing
- Invalid partitions only apply to boundary value analysis
Correct answer: Each invalid partition should be covered by a separate test case
Each invalid partition should have its own test case to avoid masking errors, as multiple invalid inputs in one test may hide failures.
Question 3: In a state machine with 4 states and 6 transitions, what is the minimum number of tests needed for transition coverage (0-switch)?
- 4
- 6 (Correct answer)
- 10
- 24
Correct answer: 6
0-switch coverage requires exercising each transition at least once, so the minimum is equal to the number of transitions (6).
Question 4: A use case has 3 alternative flows in addition to the basic flow. How many test scenarios are minimally required to achieve basic use case coverage?
- 1
- 3
- 4 (Correct answer)
- 7
Correct answer: 4
Basic use case coverage requires at least one test for the basic flow plus one for each alternative flow, totaling 4 scenarios.
Question 5: Which of the following is NOT a black-box test design technique according to ISTQB?
- Equivalence partitioning
- Statement coverage testing (Correct answer)
- Boundary value analysis
- Decision table testing
Correct answer: Statement coverage testing
Statement coverage is a white-box (structural) technique; the others are black-box techniques based on specifications.
Question 6: When is decision table testing LEAST appropriate?
- When rules involve combinations of multiple conditions
- When a system has a single input with a continuous numeric range (Correct answer)
- When business logic produces different actions for different condition combinations
- When conditions interact to produce distinct outcomes
Correct answer: When a system has a single input with a continuous numeric range
Decision tables are least suitable for single continuous ranges; boundary value analysis or equivalence partitioning is more effective there.
Question 7: A tester identifies 3 equivalence classes: EC1 (valid), EC2 (invalid-low), EC3 (invalid-high). She writes one test for EC1, one for EC2, and one for EC3. Which coverage has she achieved?
- Boundary value coverage
- Full equivalence partition coverage (Correct answer)
- Pairwise coverage
- Decision coverage
Correct answer: Full equivalence partition coverage
Covering at least one value from every identified equivalence class (valid and invalid) satisfies equivalence partition coverage.
ISTQB Black-Box Test Design 4
A password field requires 8 to 16 characters.
Using 3-value BVA, which set of test values is complete?